Today more than 60 percent of Americans are worried about climate change, and it's easy to understand why. In the last year alone, record-breaking hurricanes, wildfires, heat waves, and algal blooms, all linked in one way or another to our changing climate, have affected nearly every part of the United States. The scale of the problem can be overwhelming. The latest report from the United Nations' Intergovernmental Panel on Climate Change underscored, once again, that solving the climate crisis will require a complete and unprecedented transformation of the world economy.

Such a transformation will require concerted global action — the kind that comes about when hundreds of world leaders and delegates come together for negotiations like COP24. But that doesn't mean there's nothing the average person can do to help. Reducing waste — and food waste in particular — is something that Americans can tackle at the state, city, and even individual level.

Every year, Americans throw out 400 pounds of food per person, according to the United States Department of Agriculture. By weight, food waste is the No. 1 contributor to landfills, where it decomposes and starts emitting potent greenhouse gases like methane. Some 14 percent of U.S. methane emissions come from landfills, and, accounting for emissions all along the supply chain, wasted food accounts for 2.6 percent of U.S. greenhouse gas emissions.

Food waste is not just an American problem — though we do tend to waste more than many other developed nations. As much as a third of the world's food goes to waste, according to the Natural Resources Defense Council, and if food waste were a nation, it would be the third-largest carbon emitter.

It's no surprise, then, that the IPCC's latest climate report also identified waste as a good target for greenhouse gas reductions. It's the low-hanging fruit for both local governments and individuals, according to Kate O'Neil, a professor at the University of California–Berkeley. "Food waste is a huge contributor in many ways to climate change, so cities are in a good position to say, 'We're going to reduce our greenhouse gas emissions by really tackling the biowaste issue,'" O'Neil says. "It's more straightforward than other solutions. For example, it isn't hard to set up composting centers."

There are nearly 300 food waste collection programs across the U.S. today, a sixfold increase over the last decade. San Francisco, which already recycles more of its waste than any other U.S. city, is one of nearly two dozen cities around the world committed to cutting the amount of food waste it sends to landfills in half by 2030. More broadly, the state of California passed a law in 2016 to cut the amount of organic waste going to landfills by 75 percent by 2025, and mandating that at least 20 percent of edible food waste be recovered for human consumption. A Massachusetts law bans businesses of a certain size from sending food waste to landfills, and a law on Vermont's books will prevent residents from sending food to landfills beginning in 2020.

Individual households are by far the No. 1 source of food waste in the U.S. — some 40 percent of wasted food, according to Dana Gunders, a food waste expert formerly with the NRDC — which means that, collectively, individuals can make a big dent in food waste and its climate impacts.

Composting is one way to cut back on food-related emissions. In landfills, which are anaerobic or oxygen-deprived environments, microbes digest rotting food and release methane, a greenhouse gas that is more than 25 times more potent than carbon dioxide. Composting creates an aerobic environment, and methane-producing microbes don't thrive in the presence of oxygen.

Composting is an especially good option for the parts of our food that are inedible — like banana peels or egg shells, for example — that will always go to waste. But more than two-thirds of the food scraps we throw out were edible at one time, according to Gunders, who says that not wasting the food at all could have the biggest positive effect on our climate. "The disposal phase of life is a small portion of the footprint of the food we're wasting," she says. That's because when you throw away food, you're also wasting the water used to grow crops, for example, or the fossil fuels burned to get it from the farm to the table.

"When you throw out a hamburger, that's the equivalent of taking a 90-minute shower, in terms of the water it took to produce that hamburger," Gunders continues. "Not wasting food in the first place is, from a climate perspective, a significantly more impactful step than composting."

As with all climate issues, there's no one-size-fits-all solution to food waste. "It happens for different reasons on farms than it does in restaurants than it does in stores than it does in homes, so the solutions are very different," Gunders says. At the household level, ideally everyone would be planning meals and cooking more at home, but that's not always easy or possible. Gunders' best advice, then, is to rely more on our freezers. "I think we vastly under-utilize our freezers," she says, launching into a list of unexpected foods she frequently freezes: milk, cheese (best shredded), eggs (uncooked, but scrambled), bread, pasta, herbs — the list goes on.

Of course, freezing foods can solve one problem, while contributing to another: plastic pollution. Humans throw out 300 million tons of plastic every year. About half of that is single-use plastics, like the plastic freezer bags you might use to prolong the life of your groceries — and only 9 percent of plastic is recycled. Until recently, much of the plastic waste generated in the U.S. was shipped off to China to be processed and re-purposed. But last year, China changed its policy on accepting plastic waste imports, and now much of the recyclables that would have gone overseas are instead accumulating in our nation's landfills. Reusable containers, like the silicone-based Stasher Bags — washable, silicone bags for storing food on-the-go or in the freezer — are a greener alternative to single-use plastic bags.

There are other, less direct benefits of limiting food loss for the environment, including the fact that the less food we waste, the more will be available for the world's growing population. Cutting food waste means we can feed more people without increasing deforestation or emissions. Indeed, cutting food losses in half could feed one billion more people, according to the NRDC.

"No matter how organically or sustainably we grow our food," Gunders says, "if we're not eating it, it's a terrible use of resources."